Electrical discharge machining (EDM) is a well-established machining option for manufacturing geometrically complex or hard material parts that are extremely difficult-to-machine by conventional machining processes. The non-contact machining technique has been continuously evolving from a mere tool and die making process to a micro-scale application machining alternative attracting a significant amount of research interests. In recent years, EDM researchers have explored a number of ways to improve the sparking efficiency including some unique experimental concepts that depart from the EDM traditional sparking phenomenon. Despite a range of different approaches, this new research shares the same objectives of achieving more efficient metal removal coupled with a reduction in tool wear and improved surface quality. This paper reviews the research work carried out from the inception to the development of die-sinking EDM within the past decade. It reports on the EDM research relating to improving performance measures, optimising the process variables, monitoring and control the sparking process, simplifying the electrode design and manufacture. A range of EDM applications are highlighted together with the development of hybrid machining processes. The final part of the paper discusses these developments and outlines the trends for future EDM research.

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State of the art electrical discharge machining (EDM)

Application of response surface methodology in describing the performance of coated carbide tools when turning AISI 1045 steel

Manufacturing and measurement of freeform optics

Advances in engineered surfaces for functional performance

Surface modification by electrical discharge machining: A review

Diamond Cutting of Silicon with Nanometric Finish

The surface transformation and damage in AISI O1, A2, D2 and D6 tool steels after EDM were investigated. The results show that the recast layer is composed of two distinct layers: a topmost layer solidifying inwards from the specimen surface and an intermediate layer solidifying outwards from the base of the molten metal. The depth of surface cracks is found to correlate well with the thickness of the white layer, the latter being a layer of rapidly solidified material which, depending on the tool steel material, may consist either primarily of the topmost recast layer, or both the topmost and a large part of the intermediate recast layer. The density of surface cracks, however, correlates better with the thickness of the overall recast layer. Attempts were made to quantify the depth of white (or damaged) layer with respect to the process parameters and surface roughness after EDM. It is found that with a fixed dielectric and flushing condition, the damaged layer correlates well with the pulse energy irrespective of the tool steel material. On the other hand, even though the thickness of the white layer increases with the surface roughness, the result shows considerably more scatter. Based on the present findings, ways of estimating the depth of the damaged layer produced by EDM are proposed.

Quantification of surface damage of tool steels after EDM

Observations on Polishing and Ultraprecision Machining of Semiconductor Substrate Materials

This article discusses the recent developments in grinding of advanced materials. Eighty-four journal papers published recently are briefly introduced. The topics are advances in grinding of brittle materials, grinding of silicon, dressing/truing of grinding wheels, grinding fluids, grinding of mirrors and vibration-assisted grinding, measuring/monitoring of grinding, optimization of grinding, modelling and simulation of grinding, and size effect. Ductile mode grinding of brittle materials has been and will continue to be an intensive research area because of its increasing industrial applications and academic demands for fundamental understanding of the ductile mode grinding mechanism. Highly precision manufacturing of silicon substrates faces more and more new challenges. Grinding of silicon continues to be a popular research topic. Using lasers to true and dress grinding wheels has attracted great research interest, because it has significant advantages over mechanical processes. Environmentally friendly grinding fluids are increasingly highly demanded. Vibration-assisted grinding is promising. Monitoring, modelling and optimization of grinding processes help to understand grinding mechanisms and achieve better grinding performance. The size effect is more prominent in grinding than turning and can be used for obtaining a controlled work-hardening surface layer with higher wear resistance and hardness.

V.C. Venkatesh

Papers

Diamond Cutting of Silicon with Nanometric Finish

Quantification of surface damage of tool steels after EDM

Observations on Polishing and Ultraprecision Machining of Semiconductor Substrate Materials

Recent developments in grinding of advanced materials

Performance evaluation of cemented carbide tools in turning AISI 1010 steel